Interferons (IFNs) display pleiotropic properties; not only do they protect cells from viral infections but they may also modulate cell growth and differentiation as well as innate and adaptive immune responses. Therapeutic applications of IFNs have proven efficacy in a variety of illnesses, including hepatitis, multiple sclerosis, and some forms of cancer. Emerging evidence has been obtained during recent years that interferons impact on molecular and cellular mechanisms implicated in the development of vascular proliferative diseases such as atherosclerosis, restenosis, and cardiac allograft vasculopathy. Further appreciation and delineation of the precise mechanisms on how interferons influence vascular proliferative disease processes could potentially facilitate the development of novel treatment options attenuating these common causes of cardiovascular morbidity and mortality.